Topic: CB550F carbs on CB500

[DaveBarbier]

Pretty carbs

I see you're planning on swapping jets while the bowls are off. I'm a fan of doing one thing at a time. Not saying don't do this, but I like to be methodical.

Yeah CT has nicer roads, NYC road are garbage. North of NYC has some nice roads, though.

[turboed13b]

The idle hangs when the slides are open too far because there isn't enough vacuum to pull fuel through and it causes a lean condition. Once the slides are lowered more vacuum is created and more  fuel is then pulled in. Once you get the bike fully warm it should idle at 1000 rpm. Leave it there and don't touch it these bikes  run crappy when cold and will need some throttle holding until it can keep its own idle.

Yeah, I've always heard this is the way it is on CB's, but out of all my CBs this is the only one that won't idle right during warm up. Are all of your 500/550s like this? Is this really a 500/550 thing?

All of mine and friends bikes need choke and throttle holding when first started. They will idle on their own in 5 min or less. My 750 doesn't need to but it has the fast idle cam so it basically does the work for me.

What is your timing like? One of my bikes suddenly started feeling really weak and eventually started to die on long rides. Somehow my timing became 10° retarded  and it made my bike feel like something was seriously wrong I went so far as changing jets and needle heights but it was just the timing. Also make sure your advance is working properly.

Other than carbs, setting my timing and checking my advance was the last thing I did. The timing was a bit off, I adjusted it, and the advance wasn't sticking. Perhaps I'll take another look again, its been like 6 months and she's been my daily.

The next thing I'm doing is adjust my fuel levels. And since I'll have the bowls off, I'd like to do another jet swap. Currently I'm using #110s and since I'm currently experiencing a bad power loss on the high end, I'm contemplating going back up to #115s, while the needle clips are at 2nd groove. It's totally bogging down at WOT. It didn't do that when I was running bigger mains. Thoughts?

I would stick with doing one thing at a time float height will change the tune. A test you can do to see if it is actually running lean at WOT is to close your choke a little bit and floor it. If it runs better then it is lean. Double check your boots for cracks and make sure the clamps are tight.

It's normal to use the choke whenever the engine is at ambient temperature, it's not only for when it's actually cold out. Even in the summer when it's 90° I need choke to start if the engine is at ambient temp. And the bike will run rough when the choke is on, that's normal.

Yeah, before I made the changes I didn't need a choke at all. Now I do only until it starts running, which I was mentioning it as progress.

When you don't need choke it means you are too rich or your petcock is leaking a little bit and pumping fuel into the carbs. A sign of being to rich is the bike starts 8 stroking. It sounds like a cam if you need a video of the sound I can make one for you.

[Matte Black]

Pretty carbs
I see you're planning on swapping jets while the bowls are off. I'm a fan of doing one thing at a time. Not saying don't do this, but I like to be methodical.
Yeah CT has nicer roads, NYC road are garbage. North of NYC has some nice roads, though.

Thanks! Wish I had the CR26 rack you got. Great build and build thread Dave.

I prefer one step at a time as well, but unfortunately I only have a few hours a week to wrench her, if I'm lucky.

...

K, Ill just accept the warm up.

I'm always checking for leaks w/ carb clean and starting fluid, pretty air tight.

I've choked to test against lean, didn't improve. I also played with switch the petcock to reserve. Nothing.

I would actually love a video of the sound.

So guys...

This morning's commute was the worst she's ever ran. Like jiffy-pop she constantly back-fired my entire trip. And even more strange, I started running on 3 cylinders then 4. Was coming in an out. Can a plug fowl and then recover?

This last time she ran this badly was the last time she got rained on, fouling #3. She got rained on last night, and I kind-of expected something. But this was really bad. Kept stalling, total power loss, dead-zones, awful.

The majority of the bogging down was when I passed 1/3 OT. Would gargle n pop and fall on its face.

I'm going to let her sit and dry a bit then check the plugs and start her up and hopefully get back to where I left off.

[DaveBarbier]

I kind of expected that it wouldn't run better. Think of it this way, your bowl levels were way out of whack some were very high (rich) and some were very low (lean). You were previously trying to tune with this setup so now, if you were close on some cylinders they're now off. Float levels 4mm below the gasket seam?

I'd go back earlier in the thread and try some basic jetting, IMS settings and needle height that people recommended for your setup. Test and do some plug chops.

If plugs are fouled then you should replace them. Not sure if they can be cleaned and reused.

Thanks! Wish I had the CR26 rack you got. Great build and build thread Dave.

 Thanks, but the CR26 rack is probably going to be a bear to tune, haha. I'm probably going to do dyno time to make it faster/easier.

[Matte Black]

Inline...

I kind of expected that it wouldn't run better. Think of it this way, your bowl levels were way out of whack some were very high (rich) and some were very low (lean). You were previously trying to tune with this setup so now, if you were close on some cylinders they're now off. Float levels 4mm below the gasket seam?
That makes sense. Your saying that when I vacuum synced, I did so with the floats out-of-whack, making things worse?

I'd go back earlier in the thread and try some basic jetting, IMS settings and needle height that people recommended for your setup. Test and do some plug chops.
By basic/IMS jet settings, are you referring to factory settings, and starting there? Factory settings of a CB500? Needle clips are at the position turboed13b recommended.

If plugs are fouled then you should replace them. Not sure if they can be cleaned and reused.
Yeah, I should start over with a new set. I'll also do a compression test as I'm worried #3 is compromised. Last fowled plug was very wet.

Thanks! Wish I had the CR26 rack you got. Great build and build thread Dave.

 Thanks, but the CR26 rack is probably going to be a bear to tune, haha. I'm probably going to do dyno time to make it faster/easier.
There's only one Dyno shop in NYC and they wont put up any of my CBs for some reason. They afraid to go WOT with a stranger's old bike? Hope you do it, I find it nerdy-rad, I'd love to see your chart.

[DaveBarbier]

I kind of expected that it wouldn't run better. Think of it this way, your bowl levels were way out of whack some were very high (rich) and some were very low (lean). You were previously trying to tune with this setup so now, if you were close on some cylinders they're now off. Float levels 4mm below the gasket seam?
That makes sense. Your saying that when I vacuum synced, I did so with the floats out-of-whack, making things worse?

Nothing really to do with syncing, but tuning, as in jetting changes, needle height, etc. ...things that alter air fuel ratio. Sync doesn't alter air fuel ratio so I don't consider that tuning per se.

I'd go back earlier in the thread and try some basic jetting, IMS settings and needle height that people recommended for your setup. Test and do some plug chops.
By basic/IMS jet settings, are you referring to factory settings, and starting there? Factory settings of a CB500? Needle clips are at the position turboed13b recommended.

What are your current carbs settings? It's very hard to follow this thread.
Fill this in...

Main:
Pilot:
Needle:
IMS:

If plugs are fouled then you should replace them. Not sure if they can be cleaned and reused.
Yeah, I should start over with a new set. I'll also do a compression test as I'm worried #3 is compromised. Last fowled plug was very wet.

Well, that would throw things.

[Matte Black]

What are your current carbs settings?

#110 Mains (Originally #120s for years)
#40 Slows (Tried #42, yikes)
Needle clips at 2nd groove (From 3rd, then 4th)
Air screws 720° out

What are your settings on your 550?

THX

[DaveBarbier]

My 550 with velocity stacks and MAC 1-4 with reverse cone muffler is:
IMS-1 turn out
Main Jet-110
Slow Jet-45
Needle Setting-3rd from top

720°...you're making me recall my Cool Boarders 3 knowledge.

I think it's time for plug chops. If I were you I'd get a few sets of plugs and get to it.

[Matte Black]

720°...you're making me recall my Cool Boarders 3 knowledge.
I think it's time for plug chops. If I were you I'd get a few sets of plugs and get to it.

Just ordered 8 more plugs.
Lol was playin with the °, haha Cool Boarders!

Sorry, few dumb questions. Can't wrench until next week, mite as well shoot the shhht...

• How responsive is your 550?
• Did you adjust your IMS to RPMs or just set them to factory?
• Did you decide to up your slows a size because your running stacks?
• Original cb500 settings are #40/#100/4th/1-out, currently I have #40/#110/2nd/2-out. The equivalent to your adjustments, I should have #42/#115/4th/1.5. But since I'm using the cb550F needles and they have a different taper, I'm assuming is the reason that 2nd groove is working so nicely is because cb550f factory clip position is 2nd. Being your saying that my adjustments were blind due to my fuel level issues, would it be a good idea to start with #42/#115/2nd/1-out or even use my cb500 needles and put the clips at 4th?

Thanks!

[DaveBarbier]

720°...you're making me recall my Cool Boarders 3 knowledge.
I think it's time for plug chops. If I were you I'd get a few sets of plugs and get to it.

Just ordered 8 more plugs.
Lol was playin with the °, haha Cool Boarders!

Sorry, few dumb questions. Can't wrench until next week, mite as well shoot the shhht...

• How responsive is your 550?

I haven't ridden any other SOHC4 but I am very happy with my 550. It's quick, has nice power and even on snap throttle it picks up quickly and I have no discernible flat spots. It's really a joy to ride.

• Did you adjust your IMS to RPMs or just set them to factory?

They're currently set at slightly different turns to get the best plug color per Flybox's recommendations. An idle plug chop.

• Did you decide to up your slows a size because your running stacks?

I had UNI filters a while ago and honestly I didn't notice any change going to stacks and color is the same. They have a screen filter in them so they're not completely open, but I doubt that does anything to restrict flow. Honestly, it just creates a more turbulent flow which reduces performance. Stock for my bike is 42 slows, I only had 45's to test and it worked out. Not sure how much different it would be with 42's.

• Original cb500 settings are #40/#100/4th/1-out, currently I have #40/#110/2nd/2-out. The equivalent to your adjustments, I should have #42/#115/4th/1.5. But since I'm using the cb550F needles and they have a different taper, I'm assuming is the reason that 2nd groove is working so nicely is because cb550f factory clip position is 2nd. Being your saying that my adjustments were blind due to my fuel level issues, would it be a good idea to start with #42/#115/2nd/1-out or even use my cb500 needles and put the clips at 4th?

I'm not a carb tuning guru. I wouldn't trust myself to tell someone what jets to run vs. others, unless it's an obvious change. Plug chops, man. You'll visually see if your main is too big or small. It might be 110, but it might be 115, might even be 105. Too many variables to guess which one will be right with the carb setup and open exhaust.

Unless someone disagrees, I'd start with the main plug chop and then go to idle plug chop. Since those ends of the throttle spectrum are largely controlled by one variable (IMS for idle* and main for WO) it puts you in a good situation for handling the rest.

* I know pilot controls that too but a size like 40 or 42 will probably be good, then fine tune with IMS.

Thanks!

[Matte Black]

I've never heard of an idle plug chop. So you adjusted your air screws based on your plug states during idle chop? Do tell.

[DaveBarbier]

I'll let Flybox elaborate if he deems necessary, but it's just a more accurate way to tell air fuel ratio at idle than trying to listen for a good idle. Take the bike for a spin to warm it up, bring it back home and idle for 5 minutes (1200 rpm or so) a with a box fan aimed at the headers. Pull the plugs and read them. You're looking for the same nice toast color. Move the IMS 1/8 (45°) turn until you're perfect.

Edit: I've had a handful of Manhattans (gaggle?) but that should still make sense.

[Matte Black]

Yeah makes sense, it's what I imagined idle plug chop was. I like the way it sounds, will try it.

I don't remember the last time I binged Manhattans

[turboed13b]

DavidBarbier has pd carbs that's why his settings are way different.

I wish I could help more but not being able to ride the bike myself makes it hard to see what is going on.

When you closed the choke slightly and did a WOT run it should of ran better if you were actually lean. No change leads me to believe that you are close to the jet size you need. Like I said I have a ton of cb550/500 and only one runs a 110 main if I could find a jet in between 105 and 110 I would of used that because my swingarm has a ton of soot on it from being rich.

[Matte Black]

DavidBarbier has pd carbs that's why his settings are way different.

I wish I could help more but not being able to ride the bike myself makes it hard to see what is going on.

When you closed the choke slightly and did a WOT run it should of ran better if you were actually lean. No change leads me to believe that you are close to the jet size you need. Like I said I have a ton of cb550/500 and only one runs a 110 main if I could find a jet in between 105 and 110 I would of used that because my swingarm has a ton of soot on it from being rich.

I said it didn't improve when I would run choked, in fact it would almost die and become unresponsive when choked... Tried multiple levels of choke, ran much worse the more choke I applied.

But, I also have a lot of soot on the outside of my muffler (where it meets my exhaust pipes) where a bit of exhaust escapes. Kind of thick.

All I can say, is within the years I've been riding her, she's been very strong 1/2 - WOT until now. Granted, I moved the needles down two steps and I didn't think that could effect the main cycle like the main jets do, so I assumed I should trying going back up to 115 or 120. I know it's all speculation without riding it yourself, but I'm open to dropping down to #105s if you think that having too rich of main jets could cause the loss of the main cycle. Literally if I WOT, she falls on her face. I want to do a plug chop but would like to get the full throttle range back first, especially while I'm adjusting my fuel levels.

Thanks!

[turboed13b]

DavidBarbier has pd carbs that's why his settings are way different.

I wish I could help more but not being able to ride the bike myself makes it hard to see what is going on.

When you closed the choke slightly and did a WOT run it should of ran better if you were actually lean. No change leads me to believe that you are close to the jet size you need. Like I said I have a ton of cb550/500 and only one runs a 110 main if I could find a jet in between 105 and 110 I would of used that because my swingarm has a ton of soot on it from being rich.

I said it didn't improve when I would run choked, in fact it would almost die and become unresponsive when choked... Tried multiple levels of choke, ran much worse the more choke I applied.

That is normal if you were lean on the top end running it with choke would improve it. The opposite test is to let your bowls fill with gas and then turn off the petcock. If riding improves then it was too rich. No change means you are pretty close on the jet eventually it will start to making popping sounds out of the exhaust when it is leaning out and then start to hesistate.

But, I also have a lot of soot on the outside of my muffler (where it meets my exhaust pipes) where a bit of exhaust escapes. Kind of thick.

Signs of being rich.

All I can say, is within the years I've been riding her, she's been very strong 1/2 - WOT until now. Granted, I moved the needles down two steps and I didn't think that could effect the main cycle like the main jets do, so I assumed I should trying going back up to 115 or 120. I know it's all speculation without riding it yourself, but I'm open to dropping down to #105s if you think that having too rich of main jets could cause the loss of the main cycle. Literally if I WOT, she falls on her face. I want to do a plug chop but would like to get the full throttle range back first, especially while I'm adjusting my fuel levels.

When you crack the throttle does it fall on its face then eventually pick back up or does hit a wall and not going and faster?

Do you have a gopro? If you have something to record all I really need is sound and I can figure out which way to go on the jet.

Thanks!